Abrading the interior surfaces of hollow ware



Jan. 19, 1954 R. G. RIEDESEL ET AL ABRADING THE INTERIOR SURFACES OF HOLLOW WARE Original Filed May 31, 1947 adequate, necessitating much hand labor.

Patented Jan. 19, 1954 ABRADIN G INTERIOR SURFACES OF HOLLOW WARE Richard G. Riedesel, Stillwater, Theodore J. Miller, St. Paul, and Lawrence A. Martin, White Bear Township, Ramsey County, Minn., assignors to Minnesota Mining & Manufacturing Company, St. Paul, Minn., a corporation of Delaware Original application May 31, 1947, Serial No.

751,590, new Patent No. 2,573,220, dated October 30, 1951. Divided and this application July 26, 1951, Serial No. 238,662

Claims.

This invention relates to abrading, grinding and/or polishing the interior surfaces of hollow ware such, for example, as aluminum cookers. pans, kettles, etc., also vats, tanks and the like.

Methods previously used have beenprincipally hand operations; and the few machines that have been tried have been crude and in- All of the said methods and machines heretofore known have had numerous defects, including particularly the inability to produce true sur-v faces. The provision of means and methods for the production of such interior surfaces is accordingly one of the objectives of this invention.

Ihe invention provides a double roll grinder wherein a piece of hollow ware is rotated about its axis and a rotating abrasive Wheel is thrust into the cavity into contact with the interior surface. The work and the wheel are then moved in relation to each other in a manner to cause the Wheel to advance along a path complementary to the said surface. A second rotating wheel, in addition to the first, is thrust into the cavity into contact with the surface. The second wheel may be held against the surface without movement other than its own rotation and the rotation of the surface.

The abrasive wheels are in the form of pulleys or rolls carrying on their peripheries endless abrasive belts.

An illustrative embodiment is hereinafter described and diagrammatically illustrated in the accompanying drawings in which:

Figures 1 and 2 are plan and side elevational views, respectively, of an abrasive belt machine for abrading the interior surfaces of hollow Ware;

Figure 3 is a front elevation of a pan and the contact wheels or rolls; and

Figure 4 is a perspectiveview of a pan.

A chuck 46 adapted to hold the workpiece that is to be abraded, such as the pan 41, is fixed on the shaft 48 of a motor 49. The motor is on a table 59 which is slidably mounted in ways 5! in a rack 52. This construction, together with the feed screw assembly 54, provides means for reciprocal axial movement of the chuck, that is, reciprocal movement in the direction of the chucks axis, as indicated by the arrows.

An abrasive belt assembly, comprising rotatably mounted pulleys 56, 51 and 58 which carry an endless abrasive belt 59, is positioned in front of the chuck 46 with the pulley 56 adjacent the face of the chuck so as to extend into the interior of the pan 4! when the latter is held in the 2 chuck. The pulley 56 has a resilient periphery and serves'as a contact Wheel or roll for pressing the belt 59 into contact with the Work. The belt passes around the wheels periphery so that the wheel 56 is, in effect, an abrasive surfaced wheel.

The wheel 56 is rotatably mounted on the end of an arm or lever 66 which pivots around a shaft 6| in a plane determined by the chucks axis. Downward movement of the lever, as indicated by the arrow in Figure 2, which is limited by the stop 62, raises the wheel 56 to bear upwardly against the inner surface of the side of the pan 4?. The belt 59 is driven by the pulley 58 which is rotated by a motor 63.

Below the belt 59 is a second abrasive belt assembly comprising rotatably mounted pulleys 66, 6'! and 68 which carry an endless abrasive belt 69, positioned with the pulley or roll 65 adjacent the face of the chuck 46 so as to extend into the interior of the pan 4? when the latter is held in the chuck. The roll or pulley 66 has a resilient periphery and serves as a contact wheel or roll for pressing the belt 69 into contact with the work, and is, in eiiect, an abrasive surfaced wheel. The roll 66 is rotatably mounted on an adjustable arm 10. The arm is pivotally supported to permit positional adjustment (up and down) of the roll 66, a nut ll being provided to lock the arm in desired position. The belt 69 is driven by the pulley 68 which is rotated by the motor 53.

In operation, the pan i? is centered in the chuck 45 and fixed therein with its concave surface that is to be abraded, facing outwardly. The stop 6'2 is then adjusted so that when the lever bears down against it,the periphery of the contact roll 55 will contact the inside edge of the pan, as indicated in Figure 3. The nut H is loosened, the arm 76 is raised or lowered until the center of the roll 66 is on a level with the center of the pan, and the nut H is then,

tightened.

The. motor 63 is started, driving the abrasive belts ESand 69 in the direction of the arrows in Figure 2; the motor is is started, rotating the pan 4'! clockwise as shown in Figures 3 and 4; and the crank 54 is then turned to advance the chuck assembly toward the belt assemblies.

When the edge of the spinning pan comes within reachof the wheel 56, the lever Gt is held (manually) downwardly against the stop 62, and a downward pressure is maintained while the chuck advances, thereby continuously pressing the wheel 55 upwardly against the inside side of 3 the pan. The said manual pressure, however, should be yieldable', so that as the chuck advances, the wheel 56- may move downwardly in response to the pressure of the converging sides of the pan and follow their contour. The net effect is to rotate the arm 60 about its pivot Bi.

and thereby to move the wheel downwardly entire inside surface of the pan will then have been abraded, the curved side area by the wheel 56, the planar bottom area by the roll 65.

Referring to Figure 4, the geometrical axis of the pan 4'5 is-represented by the dotted line ab, which is at the sametime the axis of rotation of the pan and of the chuck 56. The dotted line cd is complementary to an axial section of the inside surface of the pan and lies in a plane that is determined by the said The solid line [3 is complementary to an axial section of the inside surface of the pan and lies in a plane that is determined by the said axis;

In the above described operation of the machine, the path of the point of contact of the wheel 56 is the line ed, although in practice it is frequently desirable for the line to be slightly to the right or left of ed. This is true particularly Where, as in the described machine, the abrasion is by a belt carried by the periphery of the contact wheel as contrasted with abrading by a solid abrasive wheel. In the described machine, if the pan rotates clockwise, the preferred path of the point of abrading contact is along.

a line slightly to the right of the line ed, as indicated by the solid line H. The two lines, however, are in practice interchangeable and are so very close together that, for the purposes of this invention as defined in the claims, they are regarded as equivalents and are both embraced in the phrase a path complementary to an axial section of the surface and in the phrase in a plane that is determined by the axis of rotation of the surface, as those phrases are used herein.

The line of contact of the wheel or roll 66 is the line '53. This too may vary slightly above or below its described position, but since there is little or no lateral pressure on this roll, such variance renders little, if any, advantage.

There are numerous other variables, all of which are contemplated as coming within the scope of the claimed invention. For example, the size and shape of the contact rolls 56 and 66 may vary widely, such variance being governed largely by the size and shape of the concave surfaces being abraded. The width of the belts vary accordingly. The length of the belts may also vary. For example, one model of the machine accommodates an upper belt (59) averaging 110 inches in length, and a lower belt (69) of somewhat longer length.

The periphery of the contact roll or wheel 56 is preferably curved in cross section sufficiently to clear, or at least to complement, the circular side of the pan being abraded, as shown in Figure- 3; and the wheel itself is preferably of a sufficiently small radius to enable it to clear, or

at the most to complement, the curve between the side and bottom of the pan, as shown in Figure 2.

The lower contact roll 66, being stationary, its periphery must be shaped to conform to or complement thesurface which it abrades. Such surface being here illustrated as substantially fiat or planar, the roll 56 is consequently cylindrical with substantially straight sides. If the bottom of the pan were curved, the sides of the cylinder (the periphery of the roll) would be curved accordingly. The width of the roll is preferably sufficient to support a belt whose width extends from the edge of the area that is abraded by the upper roll as to the center of thepan, preferably to a point slightly past the center; in fact, if desired, it may extend clear across the pan to the opposite edge so as tOuhHVe approximately twice the width of the illustrated roll 66.

Although. the roll or wheel 56 is referred to hereinas the first wheel and 55 as the secand, and 56 is described and illustrated as the first to contact the work, the construction may be altered sothat 6'6 is the first to make contact, if desired. Insertion of the roll 66 may be before, during or after the operation of 56.

Transverse movement of the wheel 5% in relation .to the chuck or pan, in a plane determined by the chucks axis is here shown as being accomplished by movement of the wheel, the wheel being raised and lowered by the lever 50. It may also be accomplished by moving the chuck, e. g., the arm 66 may befixed and the chuck assembly mounted in Ways for reciprocal vertical movement; or it may be accomplished by movement of both the wheel and the chuck.

The axis of the wheel .56 is shown as lying in a plane perpendicular to the. plane of its own transverse movement. If desired, the construction may be altered so that the axis of the wheel will lie in the plane of its own transverse movement.

The peripheries of the contact rolls may vary A from hard and unyielding metal or wood or other material to very soft and/ or highly resilient rubber or other material, depending on the material being abraded, the speed of-cut andthe quality or type of finish that is desired.

The chuck and belt speeds may vary over a wide range. For example, ranges frequently employed in the illustrated machines are 600 to 2000 revolutions per minute for the chucks and. 2000 to 3500 surface feet per minute for the belts. The chuck and 'beltspeeds intheir relation to each other may also vary. Generally, a belt speed that is slow in relation to the speed of the chuck or surface being ground, produces a slow cut and a smooth finish. A higher relative belt speed increases the out but gives a rougher finish. A surface being abraded can be rotated so as to move with or against the movement of the belt. By the almost infinite number of possible combinations of relative speeds and directions of movement between the surface being abraded and the abrasive elements, a corresponding variety of kinds of finish may be obtained;

The sizes and shapes of vessels Whose interior surfaces may be abrade'd'by machines that enibo'dy this invention may vary widely.

Although the illustrated machines are designed for manual operation of the feed mechanisms they could be equipped withm'echanical feeds to make the machines partially or entirely automatic without departing from the claimed invention.

This is a division of our copending application Serial No. 751,590 filed May 31, 1947, which latter issued to Richard G. Riedesel and Lawrence A. Martin as Patent No. 2,573,220 on October 30, 1951, with claims to a single roll grinder.

What we claim is:

1. In a machine for abrading the interior surfaces of hollow ware, a work holding chuck, means for rotating the chuck, means for effecting reciprocal axial movement of the chuck; a first abrasive belt assembly comprising rotatably mounted pulleys for supporting an endless abrasive belt, one of the pulleys being positioned adjacent the face of the chuck to serve as a contact wheel to apply the belt to the slide surface of the work, means for mounting the contact wheel for movement in a plane determined by the chucks axis, and means for rotating one of the pulleys to drive the belt; and a second abrasive belt assembly comprising rotatably mounted pulleys for supporting an endless abrasive belt, one of the pulleys being positioned adjacent the face of the chuck to serve as a contact roll to apply the belt to the bottom surface of the work, and means for rotating one of the pulleys to drive the belt.

2. The device of claim 1 in which the axis of the contact wheel in the said first assembly is in a plane perpendicular to the said plane in which the contact wheel of the first assembly moves.

I 3. In a machine for abrading concave surfaces, a work holding chuck, means for rotating the chuck, means for effecting reciprocal axial movement of the chuck; a first abrasive belt assembly comprising an arm, a pulley rotatably mounted at one end of the arm, means for mounting the arm in front of the chuck with the pulley adjacent the face of the chuck to serve as a contact wheel to apply the belt to the side surface of the work, the said mounting means including a pivotal mounting for effecting rotation of the arm, at least one other pulley rotatably mounted in alignment with the contact wheel pulley, and means for rotating one of the pulleys to drive the belt; and a second abrasive belt assembly comprising rotatably mounted pulleys for supporting an endless abrasive belt, one of the pulleys being positioned adjacent the face of the chuck to serve as a contact roll to apply the belt to the bottom surface of the work, and means for rotating one of the pulleys to drive the belt.

4. The device of claim 3 in which the rotation of the first arm is in a plane determined by the chucks axis.

5. The device of claim 4 in which the axis of the contact wheel in the said first assembly is in a plane perpendicular to the said plane in which the first arm rotates.

' RICHARD G. RIEDESEL.

THEODORE J. MILLER.

LAWRENCE A. MARTIN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 110,165 Smith Dec. 13, 1870 294,766 Coy Mar. 11, 1884 1,881,162 Aurori et a1 Oct. 4, 1932 2,192,240 Richardson Mar. 5, 1940 2,470,221 Mott May 1'7, 1949 

